Variable EXTENTConst

The maximum value of a coordinate in the internal tile coordinate system. Coordinates of all source features normalized to this extent upon load.

The value is a consequence of the following:

• Vertex buffer store positions as signed 16 bit integers.
• One bit is lost for signedness to support tile buffers.
• One bit is lost because the line vertex buffer used to pack 1 bit of other data into the int.
• One bit is lost to support features extending past the extent on the right edge of the tile.
• This leaves us with 2^13 = 8192